I am the product marketing director for Oracle GoldenGate product. We have noticed your blog post on Exadata covering a description for Active Data Guard. It refers to ADG being the “preferred way of Active-Active Oracle replication”.

I’d like to request correction on this comment as ADG does not have bidirectional replication capabilities which is required for Active-Active replication. GoldenGate is a complementary product to Active Data Guard with its bidirectional replication capabilities (as well as heterogeneous database support) and it is the preferred solution for Active-Active database replication.

Please note also a correction on product name spelling, notwithstanding that at least one Oracle person read the post before that, requested a different change, but didn’t notice that error.

Comments

[…] I have no idea why I was told the following, in view of a subsequent email. Oracle Active Data Guard, first introduced in the Oracle 11g code line, is the preferred way to do […]

Gera Shegalov on
May 11th, 2011 8:32 pm

Just an explanation of the term “Active” in Active Data Guard.

ADG is an extension of the Physical Standby implementation of Data Guard. Physical Standby is a single-master replication by means of redo log streaming to remote standby sites. This is a high performance way of maintaining a physical standby copy of the primary database. It has no data type limitations (unlike Logical Standby) and has better performance and corruption protection than storage-based DR solutions. Originally customers were not able to utilize a physical standby database for anything else than DR since the standby was just mounted during redo apply.

What makes ADG Active is that ADG allows customers to open a physical standby in read-only mode and offload read-only activities such as reporting while recovery concurrently applies redo arriving from the primary database. ADG makes sure that application see consistent snapshots.

That’s Active-Active in my book, and evidently of those I met with as well. The idea that you need bi-directional replication to do Active-Active doesn’t resonate.

Gera Shegalov on
May 13th, 2011 3:01 am

Curt,

My previous comment was stated as an explanation of the product name rather than a contribution to your discussion about Active/Active.

As for the discussion, my personal (not of Oracle who is my employer) academic view is that you can’t use a blanket term Active/Active for ADG because it’s not applicable for general scenarios that include updates. Compare this to RAC where you can connect to any node to run any kind of workload. RAC is an Active/Active system par excellence. (Unlike Data Guard, RAC is not designed to span long distances between data centers). Other, more heterogeneous, example of a true Active/Active system would be database systems with bi-directional replication as mentioned in the GoldenGate comment.